The effect of impregnation strategy on methane dry reforming activity of Ce promoted Pt/ZrO2

Cataloged from PDF version of article.Dry reforming of methane has been studied over Pt/ZrO2 catalysts promoted with Ce for different temperatures and feed compositions. The influence of the impregnation strategy and the cerium amount on the activity and stability of the catalysts were investigated. The results have shown that introduction of 1 wt.% Ce to the Pt/ZrO2 catalyst via coimpregnation method led to the highest catalytic activity and stability. 1 wt.%Ce-1 wt.%Pt/ZrO2 catalyst prepared by sequential impregnation displayed inferior CH4 and CO2 conversion performances with lowest H-2/CO production ratios. 1 wt.%Ce-1 wt.%Pt/ZrO2 catalyst prepared by coimpregnation showed the highest activity even for the feed with high CH4/CO2 ratio. The reason for high activity was explained by the intensive interaction between Pt and Ce phases for coimpregnated sample, which had been verified by X-ray photoelectron spectroscopy and Energy Dispersive X-Ray analyses. Strong and extensive Pt-Ce surface interaction results in an increase in the number of Ce3+ sites and enhances the dispersion of Pt. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved

Comparative Analysis of Reactant and Product Adsorption Energies in the Selective Oxidative Coupling of Alcohols to Esters on Au(111)

Gold-based heterogeneous catalysts have attracted significant attention due to their selective partial oxidation capabilities, providing promising alternatives for the traditional industrial homogeneous catalysts. In the current study, the energetics of adsorption/desorption of alcohols (CH3OH/methanol, CH3CH2OH/ethanol, CH3CH2CH2OH/n-propanol) and esters (HCOOCH3/methyl formate, CH3COOCH3/methyl acetate, and CH3COOCH2CH3/ethyl acetate) on a planar Au(111) surface was investigated in conjunction with oxidative coupling reactions by means of temperature programmed desorption (TPD) and dispersion-corrected density functional theory (DFT) calculations. The results reveal a complex interplay between inter-molecular and surface-molecule interactions, both mediated by weak van der Waals forces, which dictates their relative stability on the gold surface. Both experimental and theoretical adsorption/desorption energies of the investigated esters are lower than those of the alcohols from which they originate through oxidative coupling reactions. This result can be interpreted as an important indication in favor of the selectivity of Au surfaces in alcohol oxidative coupling/partial oxidation reactions, allowing facile removal of partial oxidation products immediately after their generation preventing their complete oxidation to higher oxygenates. © 2016, Springer Science+Business Media New York

Electronic and vibrational properties of ultrathin Si O 2 films grown on Mo(112)

Ultrathin SiO2 films on Mo(112) were synthesized using different preparation procedures and characterized with ultraviolet photoelectron spectroscopy (UPS), metastable impact electron spectroscopy (MIES), and polarization modulation infrared reflection absorption spectroscopy (PM-IRAS). By correlating the vibrational and electronic data, an assignment of the prominent spectral features are made. The physical properties of SiO2 films near one monolayer are influenced by the Mo substrate due to the Si-O-Mo linkages, whereas films greater than two monolayers show properties comparable to bulklike silica samples. The electronic and vibrational properties of the SiO2 thin films are strongly coverage dependent. The data show that highly ordered SiO2 films can be grown up to one monolayer, whereas films with a thickness of greater than one monolayer are amorphous

Multilocus Microsatellite Typing (MLMT) of Strains from Turkey and Cyprus Reveals a Novel Monophyletic L. donovani Sensu Lato Group

In eastern Mediterranean, leishmaniasis represents a major public health problem with considerable impact on morbidity and potential to spread. Cutaneous leishmaniasis (CL) caused by L. major or L. tropica accounts for most cases in this region although visceral leishmaniasis (VL) caused by L. infantum is also common. New foci of human CL caused by L. donovani complex strains were recently described in Cyprus and Turkey. Herein we analyzed Turkish strains from human CL foci in Çukurova region (north of Cyprus) and a human VL case in Kuşadasi. These were compared to Cypriot strains that were previously typed by Multilocus Enzyme Electrophoresis (MLEE) as L. donovani MON-37. Nevertheless, they were found genetically distinct from MON-37 strains of other regions and therefore their origin remained enigmatic. A population study was performed by Multilocus Microsatellite Typing (MLMT) and the profile of the Turkish strains was compared to previously analyzed L. donovani complex strains. Our results revealed close genetic relationship between Turkish and Cypriot strains, which form a genetically distinct L. infantum monophyletic group, suggesting that Cypriot strains may originate from Turkey. Our analysis indicates that the epidemiology of leishmaniasis in this region is more complicated than originally thought

Controlling the surface dispersion of BaO domains on NOx storage materials via TiO2 anchoring sites

In an attempt to control the surface dispersion and the mobility of BaO domains on NOx storage materials, TiO2/TiOx anchoring sites were introduced on/inside the conventional γ-Al2O3 support matrix. BaO/TiO2/γ-Al2O3 ternary oxide materials were synthesized via two different sol-gel preparation techniques, with varying surface compositions and morphologies. The synthesized NOx storage materials were studied via XRD, Raman spectroscopy, BET surface area analysis, TPD, XPS, SEM, EDX-mapping and in situ FTIR spectroscopy of adsorbed NO2. NOx uptake properties of the BaO/TiO2/γ-Al2O3 materials were found to be strongly influenced by the morphology and the surface structure of the TiO2/TiOx domains. The presence of Ti4+ surface sites provide additional NOx adsorption sites which can store NOx predominantly in the form of bridged/bidentate nitrates. An improved Ba surface dispersion was observed for the BaO/TiO2/γ-Al2O3 materials synthesized via the co-precipitation of alkoxide precursors which was found to originate mostly from the increased fraction of accessible TiO2/TiOx sites on the surface. These TiO2/TiOx sites function as strong anchoring sites for surface BaO domains and can be tailored to enhance surface dispersion of BaO. TPD experiments suggested the presence of at least two different types of NOx species adsorbed on the TiO2/TiOx sites, with distinctively different thermal stabilities. The relative stability of the NOx species adsorbed on the BaO/TiO2/γ-Al2O3 system was found to increase in the following order: NO+/N2O3 on alumina < nitrates on alumina < surface nitrates on BaO < bridged/bidentate nitrates on large/isolated TiO2 clusters < bulk nitrates on BaO on alumina surface and bridged/bidentate nitrates on small TiO2 crystallites homogenously distributed on the surface < bulk nitrates on the BaO sites located on the TiO2 domains

Seroprevalence of canine visceral leishmaniasis around the Aegean cost of Turkey [Ki{dotless}yi{dotless} ege bölgesindeki köpeklerde visseral leishmaniasis'in seroprevalansi{dotless}]

Visceral leishmaniasis (VL) is an infectious and zoonotic disease of people, wild and domestic mammals residing in tropical and subtropical climate zone. VL is a potential risk for human health and regarding the economical loss as a result of the disease, endemic areas should be recognized the effective implementation of control measures, and detailed epidemiological surveys should be performed in an attempt to obtain information about the incidence and prevalence of the disease in locations where the disease is diagnosed. Besides, in our country, most of the traveling has been drifted to areas dominating Mediterranean climate increasing the importance of investigations on visceral leishmaniais in Aegean region. In this study, it was aimed to determine the seroprevalence of the infection from Selçuk/İzmir, Turgutlu/Manisa, Aydi{dotless}n city province, Kuşadasi{dotless}/Aydi{dotless}n, Marmaris/Mugla, Bodrum/Mugla in stray dogs that are regarded as the main reservoirs for Visceral Leishmaniasis. For this purpose, anti-leishmania antibodies were determined with immunofluorence antibody diagnostic prosedure in serum samples obtained from untreated and unprotected 300 stray dogs located in these settlements. According to the results of the study 27 (9%) out of a total 300 dogs were infected with canine visceral leishmaniasis (CanL). It was considered that the result of this study may be used as a reference for further studies regarding human and dogs residing in Turkey